Tree stand



FIG. 1 is a top perspective view of a tree stand showing our new design;

FIG. 2 is a top plan view thereof; and,

FIG. 3 is a top side perspective view thereof, with a tree being shown in broken lines for illustrative purposes only and forming no part of the claimed design.

Those portions of the design that are not shown form no part of the claimed design and are disclaimed. 

The ornamental design for a tree stand, as shown and described. 